In the heart, the mitral valve is located between the left atrium and the left ventricle, while the tricuspid valve is located between the right atrium and the right ventricle. Each valve consists of thin leaflets, located between the atrium and the ventricle. The valve leaflets are attached to the inner wall of the ventricle by a series of fibers called chordae. In a healthy heart, when the ventricles contract during systole, the valve leaflets are apposed and thus prevent backflow of blood from the ventricle into the atrium. When the ventricles relax during diastole, the valve opens to allow blood to flow from the atrium into the ventricle.
In mitral valve prolapse, the chordaes have become elongated due to myxomatous degeneration in which collagen in the heart structures forms abnormally and causes thickening, enlargement, and redundancy of the leaflets and chordae. In addition this process may causes rupture of chordae. Under these conditions, the leaflets prolapse (flap backwards into the left atrium) during systole when the ventricles contract, allowing regurgitation of blood through the valve from the ventricle into the atrium. When severe, mitral regurgitation leads to heart failure and abnormal heart rhythms.
Mitral valve prolapse is the most common heart valve abnormality, affecting five to ten percent of the world population. Significant (moderate to severe) mitral regurgitation is much less common. For example, in one study of two million untreated people in the U.S., moderate or severe mitral regurgitation was found to occur in about 2-3 percent of people
Surgery is required for people with severe mitral regurgitation. Guidelines from the American Heart Association and European Society of Cardiology define a person as having severe chronic mitral regurgitation based upon echocardiogram measurements of the heart, heart valves, and blood flow. Mitral valve surgery is a major, open-heart, surgical procedure. The heart is arrested during critical parts of the operation, while oxygenated blood is pumped throughout the body with a heart-lung machine. A small part of the heart is then opened to expose the mitral valve.
Methods for non-invasive or minimally invasive mitral valve prolapse repair have been developed.
One method for treating heart valve prolapse involves binding together the two leaflets along the free edges of the leaflets using a clip. A method and system for suturing valve leaflets is disclosed, for example, in U.S. Pat. No. 8,062,313 to Kimblad. A clip for holding together valve leaflets is disclosed, for example, in U.S. Pat. No. 8,029,518 to Goldfarb et al.
Another method of valve repair involves introducing one or more artificial filaments to replace torn chordate. The filaments, sometimes referred to as “neochordae”, are attached at one end to a valve leaflet and at another end to cardiac tissue. A system of this type is disclosed, for example, in U.S. Pat. No. 8,043,368 to Crabtree. These methods require reliable determination of the required length of the neochordae to be introduced, which can be difficult to obtain in a beating heart. In most systems of this type it is difficult to adjust the lengths of the neochordae after deployment.